package com.dp.service.impl;

import com.dp.dto.Result;
import com.dp.entity.VoucherOrder;
import com.dp.mapper.VoucherOrderMapper;
import com.dp.service.ISeckillVoucherService;
import com.dp.service.IVoucherOrderService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.dp.utils.RedisIdWorker;
import com.dp.utils.UserHolder;
import org.redisson.api.RLock;
import org.redisson.api.RedissonClient;
import org.springframework.aop.framework.AopContext;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.core.io.ClassPathResource;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.script.DefaultRedisScript;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.PostConstruct;
import javax.annotation.Resource;
import java.util.Collections;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;


@Service
public class VoucherOrderServiceImpl extends ServiceImpl<VoucherOrderMapper, VoucherOrder> implements IVoucherOrderService {

    @Resource
    private ISeckillVoucherService iSeckillVoucherService;

    @Resource
    private RedisIdWorker redisIdWorker;

    @Autowired
    private StringRedisTemplate stringRedisTemplate;

    @Resource
    private RedissonClient redissonClient;

//    @Override
//    public Result seckKillVoucher(Long voucherId) {
//        // 1.查询优惠券
//        SeckillVoucher voucher = iSeckillVoucherService.getById(voucherId);
//        //2.判断秒杀是否开始
//        if (voucher.getBeginTime().isAfter(LocalDateTime.now())) {
//            //尚未开始
//            return Result.fail("秒杀尚未开始");
//        }
//        //3.判断秒杀是否结束
//        if (voucher.getEndTime().isBefore(LocalDateTime.now())) {
//            //已经结束
//            return Result.fail("秒杀已经结束！");
//        }
//        //4.判断库存是否充足
//        if (voucher.getStock() < 1) {
//            //库存不足
//            return Result.fail("库存不足！");
//        }
//        // 用户id
//        Long userId = UserHolder.getUser().getId();
////        synchronized (userId.toString().intern()) { //保持同一id 一把锁
//        //创建锁对象
////        SimpleRedisLock redisLock = new SimpleRedisLock("order:" + userId, stringRedisTemplate);
//
//        //使用redisson 获取锁
//        RLock lock = redissonClient.getLock("lock:order:" + userId);
//        //获取锁
////        boolean b = redisLock.tryLock(1200);
//
//        boolean b = lock.tryLock();
//        if (!b){
//            //获取锁失败  返回错误或重试
//            return Result.fail("一人一单");
//        }
//        try {
//            //获取锁成功  获取代理对象
//            //动态代理对象事务 this直接调用为非代理对象 无事务功能 spring事务失效可能性之一
//            // Spring事务想要生效，还得利用代理来生效
//            IVoucherOrderService  o = (IVoucherOrderService) AopContext.currentProxy();
//            return o.creatVoucherOrder(voucherId);
//        } finally {
//            lock.unlock();
//        }
////        }
//    }

    // 初始化加载脚本
    private static final DefaultRedisScript<Long> SECKILL_SCRIPT;

    static {
        SECKILL_SCRIPT = new DefaultRedisScript<>();
        SECKILL_SCRIPT.setLocation(new ClassPathResource("seckill.lua"));
        SECKILL_SCRIPT.setResultType(Long.class);
    }

   private IVoucherOrderService proxy;

    private BlockingQueue<VoucherOrder> orderTasks =
            new ArrayBlockingQueue<>(1024 * 1024);

    //异步处理线程池
    private static final ExecutorService SECKILL_ORDER_EXECUTOR =
            Executors.newSingleThreadExecutor();

    @PostConstruct
    private void init() {
        SECKILL_ORDER_EXECUTOR.submit(new VoucherOrderHandler());
    }
        // 用于线程池处理的任务
    // 当初始化完毕后，就会去从对列中去拿信息
    private class VoucherOrderHandler implements Runnable{

        @Override
        public void run() {
            while (true){
                try {
                    // 1.获取队列中的订单信息
                    VoucherOrder voucherOrder = orderTasks.take();
                    // 2.创建订单
                    handleVoucherOrder(voucherOrder);
                } catch (Exception e) {
                    log.error("处理订单异常", e);
                }
            }
        }

        private void handleVoucherOrder(VoucherOrder voucherOrder) {
            //1.获取用户  不可从UserHolder中取出
            Long userId = voucherOrder.getUserId();
            // 2.创建锁对象
            RLock redisLock = redissonClient.getLock("lock:order:" + userId);
            // 3.尝试获取锁
            boolean isLock = redisLock.tryLock();
            // 4.判断是否获得锁成功
            if (!isLock) {
                // 获取锁失败，直接返回失败或者重试
                log.error("不允许重复下单！");
                return;
            }
            try {
                //注意：由于是spring的事务是放在threadLocal中，此时的是多线程，事务会失效
                proxy.createVoucherOrder(voucherOrder);
            } finally {
                // 释放锁
                redisLock.unlock();
            }
        }
    }


    @Override
    public Result seckKillVoucher(Long voucherId) {
        Long userId = UserHolder.getUser().getId();
        //1.执行lua 脚本
        Long result = stringRedisTemplate.execute(SECKILL_SCRIPT,
                Collections.emptyList(),   // 脚本中  无 key类型的参数 直接传空集合
                voucherId.toString(), userId.toString());
        int i = result.intValue();
        //2.判断结果是否为0
        if (i != 0) {
            //2.1 不为0 代表没有购买资格
            return Result.fail(i == 1 ? "库存不足" : "一人一单 不能重复下单");
        }
        //TODO 2.2 为0 有购买资格 把下单信息保存到阻塞队列
        VoucherOrder voucherOrder = new VoucherOrder();
        // 2.3.订单id
        long orderId = redisIdWorker.nextId("order");
        voucherOrder.setId(orderId);
        // 2.4.用户id
        voucherOrder.setUserId(userId);
        // 2.5.代金券id
        voucherOrder.setVoucherId(voucherId);
        // 2.6.放入阻塞队列
        orderTasks.add(voucherOrder);

        //3.获取代理对象
        proxy = (IVoucherOrderService)AopContext.currentProxy();
        //4. 返回订单id
        return Result.ok(orderId);
    }


    @Transactional
    public  void createVoucherOrder(VoucherOrder voucherOrder) {
        Long userId = voucherOrder.getUserId();
        // 5.1.查询订单
        int count = query().eq("user_id", userId).eq("voucher_id", voucherOrder.getVoucherId()).count();
        // 5.2.判断是否存在
        if (count > 0) {
            // 用户已经购买过了
            log.error("用户已经购买过了");
            return ;
        }

        // 6.扣减库存
        boolean success = iSeckillVoucherService.update()
                .setSql("stock = stock - 1") // set stock = stock - 1
                .eq("voucher_id", voucherOrder.getVoucherId()).gt("stock", 0) // where id = ? and stock > 0
                .update();
        if (!success) {
            // 扣减失败
            log.error("库存不足");
            return ;
        }
        save(voucherOrder);

    }

}
